请问Android编写的时钟，如何用两个按钮控制它的开始和暂停？

这是线程 ，该怎么弄？

 @Override
protected void onAttachedToWindow() {
    super.onAttachedToWindow();
    start();
}

@Override
protected void onDetachedFromWindow() {
    super.onDetachedFromWindow();
    stop();
}
public void start(){
    if (running==false){
        running = true;
        Thread t = new Thread(new TimerTask());
        t.start();
    }
}
public void stop(){
    running = false;
}